Killer whales take advantage of warming Arctic to hunt bowhead whales in new waters

Scientists have evidence of killer whale predation on bowhead whales in the eastern Chukchi and...
Scientists have evidence of killer whale predation on bowhead whales in the eastern Chukchi and Beaufort seas for the first time.(Courtesy NOAA Fisheries)
Published: Sep. 17, 2020 at 6:41 PM AKDT
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ANCHORAGE, Alaska (KTUU) - The Arctic is warming at a rate faster than the global average, which presents an array of challenges to people in Alaska’s northernmost communities.

Now, Alaska Native subsistence hunters aren’t alone in their hunt for bowhead whales. For the first time, scientists have direct evidence of killer whales killing bowheads in the Eastern Chukchi and Beaufort Seas.

“It’s big. We didn’t know this, so this is new science,” Amy Willoughby, a biologist with NOAA Fisheries, said. “In other areas of the bowhead’s migrational pattern in other stocks of bowhead whales, killer whale predation has been fairly well documented and up until a few years ago, we didn’t know that killer whales were predating on bowhead whales in these waters, and now we do.”

NOAA states that Alaska Native hunters on St. Lawrence Island have reported seeing bowhead whales that appeared to have been killed by orcas.

Warming water temperatures and reduction of sea ice are believed to be the main contributing factors to the relatively new killer whale behavior. St. Lawrence Island sits south of the Bering Strait in the Bering Sea, where there is more time with open water and overlap between the two species.

“Formerly, we understood that there were choke points along their migratory route that wouldn’t allow killer whales to access the waters, and their access has become longer through the open water season, which would allow them more access to bowhead whales,” Willoughby said. “The other aspect of it is that bowhead whales are thought to evade predation by escaping into thicker ice, and without that ice there, they’re not able to use that avoidance strategy.”

For several decades, scientists have studied Alaska’s bowhead whales through aerial surveys and inspection of whales harvested by Alaska Native people. The investigation into killer whale predation on bowheads was triggered after an aerial survey in 2015 when biologists saw a bowhead calf that appeared to have been attacked by a killer whale.

After reviewing aerial imaging data from 2009 to 2018, the researchers determined that 18 bowhead whales had significant injuries because of killer whale attacks.

The implications of the findings are uncertain, but Willoughby says establishing baseline information will be beneficial for future studies.

The research was a collaborative project among divisions within NOAA Fisheries, the University of Washington, the North Slope Borough Department of Wildlife Management and the University of Alaska Fairbanks.

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